1. Field of the Invention
The current invention relates to a system for releasing a towing unit from a towed unit, e.g., a trailer. In particular, the invention is adapted to assist the driver of a towing unit with releasing a king pin of the trailer from a locked position behind the fifth wheel of the commercial towing unit.
2. Background Art
The interlocking apparatus for connecting a truck and trailer is comprised of components on both the truck and the trailer, which mate to achieve a mechanical connection. Typically, the truck is equipped with a locking assembly, known in the heavy trucking industry as a fifth wheel hitch, and the trailer is equipped with an apparatus known in the industry as a king pin. The king pin extends downwardly from an underside of the trailer, perpendicular to a bolster plate to which it is attached, the bolster plate being mounted to the bottom surface of the trailer. The fifth wheel hitch includes a rearwardly pivoting hitch plate having a throat with its open end facing rearward to receive the king pin as the truck is backed toward the trailer. The fifth wheel hitch also includes a locking mechanism for locking the king pin in the throat of the hitch plate. The hitch plate is generally slanted downwardly toward the rear of the truck.
To couple a vehicle, such as a commercial truck, to a trailer, the driver must continually estimate the position of the vehicle, relative to the trailer, while maneuvering the vehicle into alignment with the trailer. In practice, this may involve exiting the truck to determine the position of the truck relative to the trailer and then re-entering the truck to maneuver it into alignment. In addition, the driver utilizes his rear view side mirrors to approximate the lateral alignment between the truck and trailer. It is also necessary to align the trailer king pin vertically with the throat in the hitch plate. This is done by a conventional lift mechanism in the trailer that raises and lowers the front end of the trailer. Vertical alignment is often judged only by xe2x80x9cfeel,xe2x80x9d or guess. This practice often leads to high or low coupling and, possibly, lateral misalignment between the truck and trailer.
When backing up the towing unit, the driver often experiences difficulty in aligning the throat of the hitch plate with the king pin. For instance, the height of the king pin relative to the throat may be such that proper mating between the two will not be achieved, even though the two may be laterally aligned. In these instances, the front lower edge of the trailer may crash into the fifth wheel hitch plate (trailer and king pin too low) or the cab of the truck may crash into the body of the trailer (trailer and king pin too high). With an optimum connection, the weight of the trailer will rest upon the fifth wheel hitch plate, which normally has a downward angle. As the trailer weight is applied to the hitch plate, the angle of the fifth wheel hitch plate will flatten out into a horizontal position beneath the trailer and match the aforementioned bolster plate in a face to face manner. In this instance, the king pin will enter the throat of the hitch plate and be locked in place.
However, it is the situation of having a king pin too high, the king pin passes entirely over the top of the hitch plate and becomes trapped behind (i.e., in front of the front edge of ) the fifth wheel. That paves the way for the current invention. When the cab of a truck is driven back far enough to hit the front portion of the trailer, a situation arises where the king pin can be trapped behind the fifth wheel. This occurs because the fifth wheel hitch plate is mounted with a pivotal mount that allows the trailer weight to flatten out the fifth wheel. When the king pin is slightly higher than the open receiving portion of the fifth wheel hitch plate, the king pin will maintain enough weight to force the fifth wheel hitch plate to horizontally position itself as the king pin passes over the hitch plate. However, at such time as this occurs, the king pin will not enter the throat and lock, but rather pass completely over the top of the fifth wheel hitch plate. Once the king pin passes the hitch plate, the fifth wheel hitch plate pivots back to the standard rear-facing angle, where it is positioned behind the king pin. At this point, the king pin is locked or trapped and can no longer become free of the fifth wheel without further human assistance.
The most common remedy for this situation involves a set of rather dangerous circumstances. A second person must assist the driver by standing in the rear of the towing unit, usually between the sets of rear tires. This is due to the natural slant of the fifth wheel hitch plate that must be forced into a horizontal position. The second person must push the front of the fifth wheel hitch plate in a downward direction, or lift the rear in an upward direction. Commonly a crow bar or scrap metal is used in order to cause the pivotal fifth wheel to lie back in the horizontal position. Meanwhile, the driver pulls forward unable to see the person assisting him because the standing location is a blind spot for the driver. The potential for accidents is high and the results desired are not always guaranteed.
In the event that the prior remedy should fail, Hi-lows are pulled off of the job and placed on either side of the trailer in order to lift it far enough for the driver to pull the truck forward and release the king pin. The final alternative is attaching a wrecker to the front portion of the trailer and raising the king pin thus, allowing the driver to pull forward. Both situations give rise to wasted time and money for the driver and for the workers being pulled off of their jobs.
As the case is once in a while, the driver of a commercial vehicle could be picking up a trailer after working hours. In the event that a king pin is locked, a driver could be stuck for hours waiting for someone to come along and help. This causes unnecessary frustration on the driver and a time restraint on meeting a deadline for delivery often associated with the trucking industry.
As a result, systems have been developed to provide an output signal to the driver indicating the position of the truck relative to the trailer. Notably, known systems are targeted toward xe2x80x9cball and hitchxe2x80x9d coupling market and are not easily adaptable to the heavy trucking industry.
Known alignment systems use a variety of technologies to measure lateral offset and vertical alignment. Primarily, these systems utilize infrared sensor technology with a modulated pulsed beam. As such, these systems are limited in range (typically less than 20 feet) and require separate sets of infrared sensors on the towing and towed units, respectively, to indicate the lateral offset and vertical alignment. Also, because the infrared emitters and sensors are required on both the towing and towed units, the system must include a remote, powered transmitter on the towed unit. Clearly, these systems are limited in their application, inconvenient, and relatively expensive. In addition, should the maneuvering system fail, there is no safe procedure for releasing the trapped king pin.
The fifth wheel helper is designed to assist the driver of a commercial towing unit with the ability to release a locked king pin without the assistance of another person. Quite simply, the fifth wheel helper attaches to the frame of a towing unit just under the fifth wheel. Thus, causing the fifth wheel to lay in a horizontal position flush under the king pin. This allows the driver to pull safely forward without fear of another person physically holding the fifth wheel in the horizontal position.
The physical structure of the fifth wheel helper is a metal reinforced two by four block of wood. A second embodiment would be of hard plastic, or steel. One side is angled to slide under the fifth wheel and an indentation on the under side allows the invention to rest on the frame of the towing unit. Due to potential variations in frame size, a locking bolt is in place to tighten the grip of the fifth wheel helper to the frame. This is to prevent the fifth wheel helper from falling while the driver is pulling forward.
The main objective of the fifth wheel helper is to promote safety in the joining procedure between the towing unit and the commercial trailer, once a locked king pin situation arises. The opportunity for losing limbs or life is too high when a second person must stand in the driver""s blind spot between sets of tires.
Additional safety is obtained when thought is directed towards the hours of wasted time that truck drivers must make up in order to beat deadlines. A rushed freight driver is a dangerous hazard to the safety of not only themselves, but other road traffic as well.